csytrf_aa.f man page




subroutine csytrf_aa (UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO)

Function/Subroutine Documentation

subroutine csytrf_aa (character UPLO, integer N, complex, dimension( lda, * ) A, integer LDA, integer, dimension( * ) IPIV, complex, dimension( * ) WORK, integer LWORK, integer INFO)



 CSYTRF_AA computes the factorization of a complex symmetric matrix A
 using the Aasen's algorithm.  The form of the factorization is

    A = U*T*U**T  or  A = L*T*L**T

 where U (or L) is a product of permutation and unit upper (lower)
 triangular matrices, and T is a complex symmetric tridiagonal matrix.

 This is the blocked version of the algorithm, calling Level 3 BLAS.


          UPLO is CHARACTER*1
          = 'U':  Upper triangle of A is stored;
          = 'L':  Lower triangle of A is stored.


          N is INTEGER
          The order of the matrix A.  N >= 0.


          A is REAL array, dimension (LDA,N)
          On entry, the symmetric matrix A.  If UPLO = 'U', the leading
          N-by-N upper triangular part of A contains the upper
          triangular part of the matrix A, and the strictly lower
          triangular part of A is not referenced.  If UPLO = 'L', the
          leading N-by-N lower triangular part of A contains the lower
          triangular part of the matrix A, and the strictly upper
          triangular part of A is not referenced.

          On exit, the tridiagonal matrix is stored in the diagonals
          and the subdiagonals of A just below (or above) the diagonals,
          and L is stored below (or above) the subdiaonals, when UPLO
          is 'L' (or 'U').


          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(1,N).


          IPIV is INTEGER array, dimension (N)
          On exit, it contains the details of the interchanges, i.e.,
          the row and column k of A were interchanged with the
          row and column IPIV(k).


          WORK is REAL array, dimension (MAX(1,LWORK))
          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.


          LWORK is INTEGER
          The length of WORK. LWORK >= MAX(1,2*N). For optimum performance
          LWORK >= N*(1+NB), where NB is the optimal blocksize.

          If LWORK = -1, then a workspace query is assumed; the routine
          only calculates the optimal size of the WORK array, returns
          this value as the first entry of the WORK array, and no error
          message related to LWORK is issued by XERBLA.


          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.


November 2017

Definition at line 134 of file csytrf_aa.f.


Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

The man page csytrf_aa(3) is an alias of csytrf_aa.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK